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Unable to install OS X Yosemite on Mid-2011 iMac

I’ve been unable to install Yosemite on a mid-2011 iMac. Apple are aware, but so far haven’t been able to help. Here’s the story.

2014-10-17 Update → Although I sent a RADAR bug report, Apple weren’t able to fix this before releasing the final version of Yosemite. I tried installing that version on our iMac, and it again failed, wiping out the startup drive. Hopefully this doesn’t affect too many others.

2014-10-12 Update → I’ve now determined that the problem is not with the SSD, but something related to the machine itself. Instead of installing Yosemite on the SSD, I tried installing it on the backup drive, an internal 1TB Hitachi drive. The exact same thing happened — Upon reboot, the startup progress bar proceeded about half-way across, and then I got the “no-system” icon. When trying to restore the backup drive from the SSD, I got the same “volume is unreadable” error (requiring reinitialization) and then when trying to restore the backup drive, I got the same “OS X reports read/write errors on the drive” from Carbon Copy Cloner. So again, exactly the same experience when trying to install on the backup drive as I had when installing on the primary SSD.

Original post → I’ve been unable to install the Mac OS X 10.10 Yosemite GM 1 on my mid-2011 27″ iMac, and wanted to document the problem here in case others are running into the same issue. (Maybe somebody will have a solution!)

The startup drive is an Apple SSD. It’s not the original SSD delivered with the iMac, but rather a replacement unit installed by technicians at the Apple Store when the original SSD died last year:

After running the installer, when the computer reboots, the progress bar proceeds about 75% across, and then the circle-with-a-line-through-it icon appears on the screen, indicating that no bootable system exists on the startup drive.

When I then boot from the backup drive (an internal 1TB hard disk), a “This disk is unrecognized. Would you like to format it?” warning appears related to the SSD, requiring me to completely reformat it.

Then, when I use Carbon Copy Cloner to try to restore the startup SSD from the backup, it displays an error along the lines of “The OS is reporting read/write problems with this drive. Do you really wish to continue?”. I do continue, and the restore completes, the computer can boot and run without problems again from the SSD.

I haven’t found much on the internet about this, but one article in particular would seem to indicate that the SSD isn’t compatible with Yosemite due to Yosemite-related new security systems. However, booting into safe mode and running the Terminal commands listed in the article didn’t solve the problem on my system.

Published inTechnology


  1. Fredrik Fredrik

    Hello. Found a solution? I’m thinking about installing a INTEL SSD in my 27″ Mid 2011 iMac.

    • Hello Fredrik, I haven’t found a solution. Apple contacted me requesting some additional information (since I filed a RADAR bug report), but they asked for data from the damaged volume, which isn’t available. In the meantime, I’ve determined that the problem is not with the SSD; rather, it’s something related to the machine. I’ve just added the additional information at the end of this article, if you want to refresh and have a read.

      • Fredrik Fredrik

        Ah, ok. Thanks. Would be nice with an update when you have solved the problem.

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